JAM2

Tight junctions represent one mode of cell-to-cell adhesion in epithelial or endothelial cell sheets, forming continuous seals around cells and serving as a physical barrier to prevent solutes and water from passing freely through the paracellular space. The protein encoded by this immunoglobulin superfamily gene member is localized in the tight junctions between high endothelial cells. It acts as an adhesive ligand for interacting with a variety of immune cell types and may play a role in lymphocyte homing to secondary lymphoid organs. [provided by RefSeq]

Full Name

junctional adhesion molecule 2

Function

Junctional adhesion protein that mediates heterotypic cell-cell interactions with its cognate receptor JAM3 to regulate different cellular processes (PubMed:11590146, PubMed:11823489, PubMed:24357068).
Plays a role in homing and mobilization of hematopoietic stem and progenitor cells within the bone marrow (PubMed:24357068).
At the surface of bone marrow stromal cells, it contributes to the retention of the hematopoietic stem and progenitor cells expressing JAM3 (PubMed:11590146, PubMed:24357068).
Plays a central role in leukocytes extravasation by facilitating not only transmigration but also tethering and rolling of leukocytes along the endothelium (PubMed:12239159).
Tethering and rolling of leukocytes are dependent on the binding by JAM2 of the integrin alpha-4/beta-1 (PubMed:12070135).
Plays a role in spermatogenesis where JAM2 and JAM3, which are respectively expressed by Sertoli and germ cells, mediate an interaction between both cell types and play an essential role in the anchorage of germ cells onto Sertoli cells and the assembly of cell polarity complexes during spermatid differentiation (By similarity).
Also functions as an inhibitory somatodendritic cue that prevents the myelination of non-axonal parts of neurons (By similarity).
During myogenesis, it is involved in myocyte fusion (By similarity).
May also play a role in angiogenesis (By similarity).

Biological Process

Cell-cell adhesionManual Assertion Based On ExperimentIMP:UniProtKB
Cellular extravasationManual Assertion Based On ExperimentIDA:UniProtKB
Hematopoietic stem cell migration to bone marrowManual Assertion Based On ExperimentIMP:UniProtKB
Leukocyte tethering or rollingManual Assertion Based On ExperimentIDA:ARUK-UCL
Lymphocyte aggregationManual Assertion Based On ExperimentIDA:ARUK-UCL
Maintenance of blood-brain barrier1 PublicationNAS:ARUK-UCL
Myoblast fusionISS:UniProtKB
Negative regulation of myelinationISS:UniProtKB
Positive regulation of lymphocyte migrationManual Assertion Based On ExperimentIDA:ARUK-UCL
Spermatid developmentISS:UniProtKB

Cellular Location

Cell membrane; Cell junction; Cell junction, tight junction. Localized at tight junctions of both epithelial and endothelial cells (By similarity).
Specifically localized within the somatodendritic compartment of neurons and excluded from the axon (By similarity).

Involvement in disease

Basal ganglia calcification, idiopathic, 8, autosomal recessive (IBGC8):
A form of basal ganglia calcification, a genetically heterogeneous condition characterized by symmetric calcification in the basal ganglia and other brain regions. Affected individuals can either be asymptomatic or show a wide spectrum of neuropsychiatric symptoms, including parkinsonism, dystonia, tremor, ataxia, dementia, psychosis, seizures, and chronic headache. Serum levels of calcium, phosphate, alkaline phosphatase and parathyroid hormone are normal. The neuropathological hallmark of the disease is vascular and pericapillary calcification, mainly of calcium phosphate, in the affected brain areas.

Topology

Extracellular: 29-238
Helical: 239-259
Cytoplasmic: 260-298